If p is a prime number, for how many values of p is p^2 + 21p - 1 also prime?

How many 5-member chess teams can be chosen from 15 interested players? Consider only the members selected, not their board positions.

How many ways can you make 7 with 2 and 1?

What is the area of the regular trapezoid below? A trapezoid has a base of 20 inches, height of 8 inches, and top side length of 12 inches. 128 Inches squared 160 Inches squared 960 Inches squared 1,920 Inches squared

Marisol scored 96% on the English test there were 50 questions on the test how many did Marisol answer correctly

Write the difference 72,25,76

An investment of d dollars at k percent simple annual interest yields $600 interest over a 2-year period. In terms of d, what dollar amount invested at the same rate will yield $2,400 interest over a 3-year period? A. (2d) / 3 B. (3d) / 4 C.

A bag contains 2 steel balls and 5 brass balls. The total weight is 13 pounds. If 2 steel balls are added and 2 brass balls are removed, the weight decreases to 12 pounds. How much does each kind of ball weigh?

A juice shop needed 360 oranges to make 40 L of fresh-squeezed juice. How many oranges would be needed to make 60 L of fresh-squeezed juice?

5) 6 (5a - 2) < 108 -1 0 1 2 3 4 5 6 7 8 9

What is x + 8 =.5?